Abstract: To examine the reliability of tissue micoroarrays (TMA) for detecting thyroid transcription factor- 1 (TTF- 1) compared to the original paraffin sections containing normal human adult type Ⅱ alveolar epithelial cells, embryonic pneumocytes, primary focus of lung carcinoma and lymph node metastasis, and to utilize this technique for detecting TTF- 1 in lung carcinoma samples. Methods: The TMA technology was used to construct a paraffin tissue microarray containing 765 tissue cores. The immunohistochemical SP method was employed to determine the TTF- 1 protein expression in both the TMA and the original conventional paraffin sections. The PU (Positive Unit) of TTF- 1 protein was assessed quantitatively with the Leica Q500MC image analysis system using results from the paired conventional full sections as controls. Results: There was no significant difference in TTF- 1 expression between TMA and paired conventional full sections in different nuclei of the lung tissue.Conclusions: TMA detection of TTF- 1 protein expression in lung carcinoma is highly concordant with that of the original paraffin sections. TMA is a reliable method for detecting protein expression.